Apparatus and method for encoding and decoding spatial parameter   

Abstract: An apparatus and method for encoding and decoding a spatial parameter are provided. A spatial parameter encoding apparatus may encode a spatial parameter using a correlation between spatial parameters indicating a characteristic relationship between channels of a multi-channel audio signal, so that the multi-channel audio signal may be efficiently encoded.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Korean Patent Application No. 10-2010-0100001, filed on Oct. 13, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

1. Field

Embodiments of the following description relate to a spatial parameter encoding apparatus and method, and a spatial parameter decoding apparatus and method. More particularly, embodiments of the following description relate to an apparatus and method for encoding and decoding a spatial parameter using a correlation between spatial parameters.

2. Description of the Related Art

Generally, a scheme of encoding a multi-channel audio signal includes waveform multi-channel audio coding, and parametric multi-channel audio coding. Here, the multi-channel audio signal refers to a signal with at least two channels.

The waveform multi-channel audio coding typically includes, for example, Moving Picture Experts Group (MPEG)-2 multi-channel audio coding, Advanced Audio Coding (AAC) multi-channel audio coding, and BSAC(Bit-sliced arithmetic coding)/AVS(Audio Video Standard) multi-channel audio coding. Additionally, the parametric multi-channel audio coding typically includes MPEG surround coding.

In particular, in the MPEG surround coding, a multi-channel audio signal may be restored using a signal obtained by down-mixing the multi-channel audio signal, and using a spatial parameter indicating a characteristic relationship between channels. Phase difference information among spatial parameters may be used to improve spatiality of an audio signal, however, may not be used to reduce a bit amount at a low bit rate. A bit amount of a spatial parameter may also be reduced by adjusting a quantization level, however, a sound quality may be degraded.

Accordingly, there is a desire for a method of improving a spatiality based on a low bit rate, even when a small amount of spatial parameters is used.

SUMMARY

According to an aspect of one or more embodiments, there is provided a spatial parameter encoding apparatus including a valid range determination unit to determine a valid range of a spatial parameter using a correlation between spatial parameters indicating a characteristic relationship between channels of a multi-channel audio signal, a parameter quantization unit to quantize the spatial parameter based on the valid range, and a parameter encoding unit to encode the quantized spatial parameter using at least one processor.

According to an aspect of one or more embodiments, there is provided a spatial parameter decoding apparatus including a spatial parameter decoding unit to decode an encoded spatial parameter, a valid range determination unit to determine a valid range of a spatial parameter using a correlation between spatial parameters indicating a characteristic relationship between channels of a multi-channel audio signal, and a parameter dequantization unit to dequantize the spatial parameter based on the valid range using at least one processor.

According to an aspect of one or more embodiments, there is provided a spatial parameter encoding method including determining a valid range of a spatial parameter using a correlation between spatial parameters indicating a characteristic relationship between channels of a multi-channel audio signal, quantizing the spatial parameter based on the valid range, and encoding the quantized spatial parameter using at least one processor.

According to an aspect of one or more embodiments, there is provided a spatial parameter decoding method including decoding an encoded spatial parameter, determining a valid range of a spatial parameter using a correlation between spatial parameters indicating a characteristic relationship between channels of a multi-channel audio signal, and dequantizing the spatial parameter based on the valid range using at least one processor.

According to another aspect of one or more embodiments, there is provided at least one computer readable medium storing computer readable instructions to implement methods of one or more embodiments.

According to one ore more embodiments, it is possible to efficiently encode a spatial parameter by removing invalid parameter information using a correlation between spatial parameters.

Additionally, according to one or more embodiments, it is possible to improve a spatiality even using a spatial parameter with a low bit rate, based on a correlation between spatial parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readily appreciated from the following description of embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 illustrates a block diagram of apparatuses used to encode a multi-channel audio signal according to one or more embodiments;

FIG. 2 illustrates a block diagram of apparatuses used to decode a multi-channel audio signal according to one or more embodiments;

FIG. 3 illustrates a block diagram of a configuration of a spatial parameter encoding apparatus of FIG. 1;

FIG. 4 illustrates a block diagram of a configuration of a spatial parameter decoding apparatus of FIG. 2;

FIG. 5A illustrates a diagram of a correlation between spatial parameters, and FIG. 5B illustrates a valid range based on the correlation according to one or more embodiments;

FIG. 6 illustrates a flowchart of a method of encoding a multi-channel audio signal according to one or more embodiments;

FIG. 7 illustrates a flowchart of an operation of encoding a spatial parameter in the method of FIG. 6;

FIG. 8 illustrates a flowchart of a method of decoding a multi-channel audio signal according to one or more embodiments; and

FIG. 9 illustrates a flowchart of an operation of decoding a spatial parameter in the method of FIG. 8.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. Embodiments are described below to explain the present disclosure by referring to the figures.

FIG. 1 illustrates a block diagram of apparatuses used to encode a multi-channel audio signal according to one or more embodiments.

Referring to FIG. 1, the multi-channel audio signal may be encoded through a down-mixing apparatus 101, a spatial parameter extracting apparatus 102, an audio signal encoding apparatus 103, a spatial parameter encoding apparatus 104, and a multiplexing apparatus 105. The encoded multi-channel audio signal may be provided as a bitstream.

The down-mixing apparatus 101 may generate a main signal by down-mixing the input multi-channel audio signal. For example, the down-mixing apparatus 101 may down-mix a stereo signal with two channels, to generate a mono signal with a single channel. In other words, the mono signal may be used as the main signal. In an example of a Moving Picture Experts Group (MPEG) surround coding, a tree structure is formed using an apparatus(2-1-2) for coding a stereo signal as illustrated in FIG. 1, and the multi-channel audio signal with at least two channels may be coded.

The spatial parameter extracting apparatus 102 may extract a spatial parameter indicting a characteristic relationship between channels of the multi-channel audio signal. For example, the spatial parameter may include at least one of an Inter-channel Intensity Difference (IID), a Channel Level Difference (CLD), an Inter-Channel Correlation (ICC) based on a similarity of waveforms of channels, an Inter-channel Phase Difference (IPD), an Inter Time Difference (ITD), and an Overall Phase Difference (OPD). Here, the IID or the CLD may indicate an intensity difference based on an energy level between channels, and the OPD may indicate how a phase difference between two channels is distributed based on a mono signal.

The spatial parameter may be determined based on a condition of the following Equation 1:

 [ Equation   1 ]   [ L R ] = [ ? ? ? ? ]  [ M D ]    ?  indicates text missing or illegible when filed

In Equation 1, M denotes a down-mix signal, and D denotes a decorrelated signal of the down-mix signal.

[ ? ? ? ? ] = { [ ? 0 0 ? ]  [ ? 1 ?  cos  (

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